selectInput reactive value in shinyDashboard sidebar of R shiny app remains Null - r

Question

It appears the input value of a selectInput object is not updating. I have inserted one in the sidebar menu. I am using shinyDashboard. here is my code.
header & Sidebar
header <-
dashboardHeader(
title = "REPORT",
tags$li(class = "dropdown",
tags$style(
HTML(
"#import url('//fonts.googleapis.com/css?family=Libre+Baskerville:400,700|Open+Sans:400,700|Montserrat:400,700');"
)
)),
disable = FALSE,
titleWidth = '200'
)
header$children[[3]]$children[[3]] <-
tags$h1("DATABASE",
# align = 'left',
style = "color:#FFFFFF; font-weight: bold; font-family: 'Open Sans','Libre Baskerville',Montserrat, serif;font-size: 23px;")
data_type_list<-c('in vivo','in vitro','pbpk')
siderbar <- dashboardSidebar(
width = 200,
sidebarMenu(
id = 'sidebar',
style = "position: relative; overflow: visible;",
menuItem(
"TK Knowlegebase",
tabName = 'tk',
icon = icon('database'),
badgeColor = "teal",
#radioButtons("tk_data_type", "Select Data Type:",data_type_list)
selectInput('tk_data_type',"Select Data Type",data_type_list, selected=1)
)
)
)
body
body <- dashboardBody(width = 870,
tags$head(
tags$link(rel = "stylesheet", type = "text/css", href = "custom.css")
),
#theme = shinythemes::shinytheme("darkly"),
tabItems(
tabItem (
tabName = "tk",
mainPanel(
#in vivo ----
conditionalPanel(
condition ="input.tk_data_type== 'in vivo'",
tags$h2('vivo')
),
# in vitro ----
conditionalPanel(
condition="input.tk_data_type== 'in vitro'",
tags$h2('vitro')
)
,
# pbpk ----
conditionalPanel(
condition="input.tk_data_type== 'pbpk'",
tags$h2('pbpk')
)
)))
server = function(input, output, session) {
observe({input$tk_data_type})
}
ui <- dashboardPage(title = 'ARC Toxkin App', skin = 'purple',
header, siderbar, body)
shiny::shinyApp(ui = ui, server = server)
I even attempted to use observe({input$tk_data_type}) in the server section to no success.
What I obtain is a blank page. what I wish to see is content from dashboardBody() appear.
Thank you for your time
UPDATE
This is a short-term fix solution, thanks to user YBS.
vitro_tabset<-tabsetPanel(
tabPanel("Detailed",
"This is a test"),
tabPanel("Phys-chem",
"This is a test"),
tabPanel("Exploratory",
"This is a test"),
tabPanel("Downloads",
"This is a test")
)
vivo_tabset<-tabsetPanel(
tabPanel("Detailed",
"This is a test"),
tabPanel("Phys-chem",
"This is a test"),
tabPanel("Exploratory",
"This is a test"),
tabPanel("Downloads",
"This is a test")
)
siderbar <- dashboardSidebar(
sidebarMenu(
id = 'sidebar',
menuItem(
"TK Knowlegebase",
tabName = 'tk',
icon = icon('database'),
badgeColor = "teal",
selected = TRUE,
startExpanded = TRUE,
#radioButtons("tk_data_type2", "Select Data Type:",data_type_list),
menuSubItem('vivo', tabName = 'vivo', icon = shiny::icon("angle-double-right"), selected = NULL),
menuSubItem('vitro', tabName = 'vitro', icon = shiny::icon("angle-double-right"), selected = TRUE),
menuSubItem('pbpk', tabName = 'pbpk', icon = shiny::icon("angle-double-right"), selected = NULL)
)
)
)
body <- dashboardBody(width = 870,
tabItems(
tabItem (tabName = "vivo",
vivo_tabset),
tabItem(tabName='vitro',
# in vitro ----
vitro_tabset),
# pbpk ----
tabItem(tabName='pbpk')

Answer 1

It appears that tabItems() and tabItem() don't work well in your program as the sidebarmenu requires minor tweaking. Also, you don't need mainPanel. Try this
data_type_list <- c("in vivo","in vitro","pbpk")
ui <- shinydashboard::dashboardPage(title = "ARC Toxkin App", skin = "purple",
shinydashboard::dashboardHeader(
title = "REPORT" ,
tags$li(class = "dropdown",
tags$style(
HTML(
"#import url('//fonts.googleapis.com/css?family=Libre+Baskerville:400,700|Open+Sans:400,700|Montserrat:400,700');"
)
)),
disable = FALSE,
titleWidth = '200'
),
shinydashboard::dashboardSidebar(width = 220,
useShinyjs(),
sidebarMenu(
id = "tabs",
style = "position: relative; overflow: visible;",
menuItem("TK Knowlegebase", tabName="tk", icon = icon("bar-chart-o"),
menuSubItem("TK Knowlegebase1", tabName = "tk1", icon = icon('database')),
selectInput("tk_data_type", label="Select Data Type", choices = data_type_list, selected=1),
menuSubItem("TK Knowlegebase2", tabName = "tk2", icon = icon('database'))
#radioButtons("tk_data_type2", "Select Data Type:",data_type_list)
)
)
),
shinydashboard::dashboardBody( #width = 870,
tags$head(
tags$link(rel = "stylesheet", type = "text/css", href = "custom.css"),
),
#theme = shinythemes::shinytheme("darkly"),
tabItems(
#tabItem(tabName = "tk", headerPanel('First')),
tabItem(tabName = "tk1",
fluidRow(
shinydashboard::box(title = "Graphics Package", width = 12, solidHeader = TRUE, status="info",
## vivo
conditionalPanel(
condition = "input.tk_data_type == 'in vivo'",
tags$h2(' vivo')
),
## in vitro
conditionalPanel(
condition = "input.tk_data_type == 'in vitro'",
tags$h2(' vitro')
),
## pbpk
conditionalPanel(
condition = "input.tk_data_type == 'pbpk'",
tags$h2(' pbpk')
),
verbatimTextOutput("tb1"),
DTOutput("tb2")
))
),
tabItem(tabName = "tk2", headerPanel('Last'), DTOutput("tb3")
#verbatimTextOutput("tb4")
)
)
)
)
server <- function(input, output, session) {
output$tb3 <- renderDT(mtcars)
output$tb2 <- renderDT(iris)
output$tb1 <- renderPrint({input$tk_data_type})
output$tb4 <- renderPrint({input$tk_data_type2})
}
shinyApp(ui, server)